Bug#1110878: Kernel module MD_LINEAR is absent in debian trixie default kernel.

[Good Grief <iamdpoke@gmail.com>]

Hello. 

We are using the next disk setup on some of our servers:

mdadm raid (concatenation (16Tb x4) and mirror (16Tb x2) ) -> cryptsetup -> lvm in each of them.

After updating debian to trixie on one of those servers I've noticed that mdadm raid1(mirror) md-s worked well but I could not decrypt md-s that use the md_linear kernel module.

Luckily, I don't have the root partition on those raids (It is located on an additional separated ssd disk) and the servers can start successfully.

So at this moment I've reverted to kernel 6.1(from bookworm debian version) to restore the data storage functionality and trying to find the solution for data migration from mdadm to dmraid or maybe lvm or something else.

After quick googling I think dmraid (dm-linear can cover my case / can create disk concatenations, but I still need to migrate a lot of data to the new raid structure %( ).

(Earlier I thought that mdadm won dmraid in "software raid battles .... ").

Best Regards,

     IG.

вт, 12 авг. 2025 г. в 20:46, Salvatore Bonaccorso <carnil@debian.org>:

Hi,

On Tue, Aug 12, 2025 at 05:36:32PM +0300, Good Grief wrote:
> Hello Salvatore.
>
>     Thank you for your quick reply.
>     So it appears that it's not a debian kernel build config bug; this
> change was made in the kernel repo not only in debian.
>     Thank you for the actual links to MD_LINEAR removal description on site
> kernel.org.
>
>     We can close this discussion branch then.
>     I don't think we should go deeply into my case. I'm going to find the
> solution for it.

But is your usecase covered with a dm-linear setup? If yes I agree
that we proceed, given it was deprecated for a while I would rather
not want to reintroduce for a release, and then getting it dropped
again.

This is the reason I'm asking if you can cover your use case with
dm-linear (or different). If yes then we go ahead with closing the
issue.

Regards,
Salvatore